Objective testing of the visually impaired has long been, and remains, a significant problem to the researcher, psychologist and related professional. Predominantly, the problem stems from an enormous variation in the types and degree of visual handicap that exist among the visually impaired population, where, for example, a method designed to test the totally blind (e.g. braille) is inappropriate for the partially sighted (most of whom have never had to learn braille). It is this great heterogeneity among visually handicapped persons that has often required workers to employ deviations from standard test procedures in individual cases, (See "Measures of Psychological, Vocational & Educational Functioning in the Blind and Visually Handicapped. New York: American Foundation for the Blind, 1976--Scholl and Schnur).
Clearly, evaluation of the visually impaired has largely been the province of specialists. However, recent trends in America and Australia within the last decade have highlighted an increasing need. The mainstreaming of visually impaired children from special to regular education has resulted in pressure on teachers and school counsellors to assess the visually handicapped as well as sighted children. In addition, as Scholl and Schnur (1976) point out, members of the helping professions, psychologists, guidance personnel and rehabilitation workers are becoming increasingly required to evaluate children and adults with visual impairments. Consequently, it would seem that professionals can only meet this challenge if they have available of appropriate resources and methodologies for modifying and adapting their procedures.
Although a variety of methods have been employed to administer tests to the visually impaired, a number of problems can be identified in relation to the more commonly used approaches. Perhaps the most common method of administering written tests has required a one to one approach, where the administrator reads the questions to the testee, and records his responses. Whilst this method can be used with both totally and partially blind individuals, its relative simplicity should be weighed against its variation in administration between testees, the dependence on an intermediary, the lack of privacy for the testee, the passive role of the testee and the time and resources required for testing large samples. Alternatively, totally blind persons have been tested with a method requiring them to mark the braille letter of their answer with a pencil, directly on the question sheet. In such cases, the testee has no means of correcting or checking over his responses. Additionally, braille adaptations have been made to some of the more frequently used tests (e.g. Minnesota Multiphasic Personality Inventory), yet only a small number of people are proficient and comfortable in the use of braille, and at best, the whole procedure is very time consuming, cumbersome and costly.
Unfortunately, even tests developed specifically for the blind present a range of disadvantages--norms tend to be based on small numbers; norms are usually biased by use of institutionalized populations; norms do not appropriately represent totally and partially blind individuals; test instructions are usually amateurish and poorly standardized; and there is too little supporting literature for the test to make its interpretation accurate.
With these points in mind, it has been suggested that the ideal would probably be a test designed for oral administration. Indeed, the Verbal Scales of the Weschler Adult Intelligence Scales were designed for oral administration and are normed on that basis, and represent the most frequently used measures of abilities for blind persons. Importantly however, oral administration is clearly inappropriate for multiple choice questions, and seems best suited to the open ended or dichotomous (e.g. true/false, yes/no) response format.